Name a common disease affecting ornamental plants in nurseries.

Powdery mildew is a common disease that affects ornamental plants in nurseries, primarily due to its broad range of host plants and favorable conditions for development. This fungal infection is characterized by the appearance of white or gray powdery spots on the leaves, stems, and flowers, which can lead to reduced vigor and aesthetic quality of the plants.

The spores of the fungus responsible for powdery mildew are easily spread through the air, making it particularly prevalent in nurseries where plants are in close proximity. High humidity and moderate temperatures tend to promote its growth, creating a common challenge for nursery operators. Effective management practices, including proper plant spacing for air circulation, timely application of fungicides, and the removal of infected plant parts, are essential to controlling this disease in ornamental plants.

In contrast, other diseases like root rot, leaf spot, and blight also affect ornamental plants, but powdery mildew holds a prominent place in nursery concerns due to its rapid spread and impact on a wide variety of species commonly grown in these settings.